Transmission module and transmission and reception module

ABSTRACT

A transmission module includes an amplifier that amplifies a plurality of transmission signals in different frequency bands, a power supply voltage regulator circuit that supplies different power supply voltages for the respective frequency bands of the transmission signals to the amplifier, and a variable matching circuit including at least one variable capacitor element and at least one fixed inductor element. The variable matching circuit satisfies different output impedance matching conditions of the amplifier for the respective frequency bands of the transmission signals by changing a capacitance value of the at least one variable capacitor element on the basis of a change in the output impedance matching conditions of the amplifier in response to a change in the power supply voltages supplied to the amplifier.

This application claims priority from Japanese Patent Application No.2016-174726 filed on Sep. 7, 2016. The content of this application isincorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates to a transmission module and atransmission and reception module.

A multi-band system that enables a single transmission module to supporta plurality of frequency bands has been studied over recent years. Inlight of this situation, U.S. Patent Application Publication No.2016/0094192 discloses a transmission module supporting such amulti-band system. In the transmission module, combinations of outputimpedance matching circuits and power amplifiers, each of which isoptimized to amplify signals in a predetermined frequency band, areprovided in parallel for individual frequency bands. Signal paths fortransmission signals of different frequencies whose powers are amplifiedby the power amplifiers are switched in a time-division manner by a bandswitch.

However, if combinations of output impedance matching circuits and poweramplifiers, each of which is optimized to amplify signals in apredetermined frequency band, are provided for respective frequencybands, the number of elements in the power amplifiers and the outputimpedance matching circuits is large. In addition, the transmissionmodule has a large area. Thus, it is difficult to meet the demand forreduced size of a mobile communication device including the transmissionmodule.

BRIEF SUMMARY

Accordingly, the present disclosure provides a transmission module thatcan support a multi-band system without necessarily an increase in thenumber of elements used.

According to embodiments of the present disclosure, a transmissionmodule includes (i) an amplifier that amplifies a plurality oftransmission signals in different frequency bands, (ii) a power supplyvoltage regulator circuit that supplies different power supply voltagesfor the respective frequency bands of the transmission signals to theamplifier, and (iii) a variable matching circuit including at least onevariable capacitor element. The variable matching circuit includes novariable inductor element. The variable matching circuit satisfiesdifferent output impedance matching conditions of the amplifier for therespective frequency bands of the transmission signals by changing acapacitance value of the at least one variable capacitor element on thebasis of a change in the output impedance matching conditions of theamplifier in response to a change in the power supply voltages suppliedto the amplifier.

According to embodiments of the present disclosure, a transmissionmodule can support a multi-band system without necessarily an increasein the number of elements used.

Other features, elements, characteristics and advantages of the presentdisclosure will become more apparent from the following detaileddescription of embodiments of the present disclosure with reference tothe attached drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a circuit configuration of a transmission andreception module according to a first embodiment of the presentdisclosure;

FIG. 2 illustrates simulation results depicting the locus of theimpedance of a variable matching circuit on a Smith chart;

FIG. 3 illustrates simulation results depicting the locus of theimpedance of the variable matching circuit on a Smith chart;

FIG. 4 illustrates a circuit configuration of the transmission andreception module according to the first embodiment of the presentdisclosure;

FIG. 5 illustrates a circuit configuration of the transmission andreception module according to the first embodiment of the presentdisclosure;

FIG. 6 illustrates a circuit configuration of a transmission andreception module according to a second embodiment of the presentdisclosure;

FIG. 7 illustrates a circuit configuration of a transmission andreception module according to a third embodiment of the presentdisclosure;

FIG. 8 illustrates a circuit configuration of a transmission andreception module according to a fourth embodiment of the presentdisclosure; and

FIG. 9 illustrates a circuit configuration of a transmission andreception module according to a fifth embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described hereinafter withreference to the drawings. The same numerals are used to indicate thesame or substantially the same circuit elements and no repeateddescription is given.

FIG. 1 illustrates a circuit configuration of a transmission andreception module 10 according to a first embodiment of the presentdisclosure. The transmission and reception module 10 supports amulti-band system and is included in a mobile communication device suchas a cellular phone to transmit and receive radio frequency (RF) signalsin a plurality of frequency bands to and from a base station. Thetransmission and reception module 10 includes a transmission module 700,a reception module 800, a baseband integrated circuit (IC) 20, a radiofrequency integrated circuit (RFIC) 30, duplexers (separators) 81, 82,and 83, an antenna switch 90, and an antenna 100. The transmissionmodule 700 is a module for amplifying the power of a transmission signaland also serves as a power amplifier module. The transmission module 700includes amplifiers 40 and 50, a variable matching circuit 60, a bandswitch 70, a power supply voltage regulator circuit 110, and a controlcircuit 120. The band switch 70 is optional to the transmission module700. As illustrated in FIG. 9, the transmission module 700 may notinclude the band switch 70. In this embodiment, the amplifiers 40 and 50are used in two stages. The number of stages in which the amplifiers 40and 50 are used may be determined as desired in accordance with theoutput of a transmission signal. The reception module 800 is a modulefor low-noise amplifying a reception signal and includes a low-noiseamplifier.

The baseband IC 20 generates a first baseband signal by performingdigital signal processing. The first baseband signal is used to generatea first transmission signal in a first frequency band (for example, the700 MHz band). The baseband IC 20 generates a second baseband signal byperforming digital signal processing. The second baseband signal is usedto generate a second transmission signal in a second frequency band (forexample, the 800 MHz band). The baseband IC 20 generates a thirdbaseband signal by performing digital signal processing. The thirdbaseband signal is used to generate a third transmission signal in athird frequency band (for example, the 900 MHz band). The RFIC 30modulates a carrier wave in accordance with information superimposed onthe first, second, and third baseband signals generated by the basebandIC 20 to respectively generate first, second, and third transmissionsignals, and outputs the generated transmission signals in atime-division manner. The first, second, and third transmission signalsare RF signals in different frequency bands.

The term “transmission signals”, as used herein, collectively refers tothe first, second, and third transmission signals, and the term“transmission signal” is used to indicate each of the first, second, andthird transmission signals unless they are individually identified. Thesame applies to the terms “reception signals” and “reception signal”described below.

The amplifiers 40 and 50 amplify the first, second, and thirdtransmission signals output in a time-division manner from the RFIC 30.The amplifier 50 functions as an output-stage amplifier, and theamplifier 40 functions as a driver-stage amplifier connected to thestage preceding the amplifier 50. The control circuit 120 receivesfrequency information and power mode information from the baseband IC20. The frequency information indicates the frequencies of therespective transmission signals, and the power mode informationindicates the transmission output levels of the respective transmissionsignals. The control circuit 120 controls the power supply voltageregulator circuit 110 so that the power supply voltage to be suppliedfrom the power supply voltage regulator circuit 110 to the amplifier 50is regulated on the basis of the frequency information and power modeinformation received from the baseband IC 20. The power supply voltageregulator circuit 110 is, for example, a DC/DC converter for boosting orstepping down a direct-current (DC) voltage serving as a power supplyvoltage to be supplied to the amplifier 50. Table 1 gives an example ofpower supply voltages for the amplifier 50 that are regulated on thebasis of frequency information and power mode information. The controlcircuit 120 may control the power supply voltage regulator circuit 110so that the power supply voltage to be supplied from the power supplyvoltage regulator circuit 110 to the amplifier 50 is regulated on thebasis of frequency information and power mode information received fromthe RFIC 30 instead of from the baseband IC 20.

TABLE 1 Frequency band Power mode 700 MHz band 800 MHz band 900 MHz bandHigh-output mode  7.2 V 7 V  6.8 V Medium-output mode 5.15 V 5 V 4.85 VLow-output mode  3.1 V 3 V  2.9 V

In the example given in Table 1, power modes are divided into threelevels of a “high-output mode”, a “medium-output mode”, and a“low-output mode”. A power supply voltage for the amplifier 50 which isrequired to amplify transmission signals in an identical frequency bandis set to a higher voltage value for a higher transmission output level.On the other hand, a power supply voltage for the amplifier 50 which isrequired to amplify transmission signals with an identical transmissionoutput level is set to a lower voltage value for a higher transmissionfrequency. As given in Table 1, the rates of change of the power supplyvoltage for the amplifier 50 over the frequency range from the 700 MHzband to the 900 MHz band are as low as 0.2 V to 0.4 V or less. When theabsolute value of the power supply voltage for the amplifier 50 has anerror, the deterioration of accuracy of the variable matching circuit 60is not small even if the error is small. As also given in Table 1, thehigher the power supply voltage for the amplifier 50 is, the higher therate of change of the power supply voltage for the amplifier 50 due tothe difference in frequency band is. Thus, a higher power supply voltagefor the amplifier 50 can suppress the deterioration of accuracy of thevariable matching circuit 60 more when the absolute value of the powersupply voltage for the amplifier 50 has an error. In a typical mobilecommunication device, the transmission and reception module 10 has abattery voltage of about 3 V to 4 V. It is thus desirable that the powersupply voltage regulator circuit 110 have a function of boosting each ofthe power supply voltages supplied to the amplifier 50 to a level higherthan the battery voltage. In this embodiment, the power supply voltageregulator circuit 110 having such a boosting function is employed.

The variable matching circuit 60 is configured to satisfy differentoutput impedance matching conditions of the amplifier 50 for thefrequency bands of transmission signals, on the basis of a change in theoutput impedance matching conditions of the amplifier 50 in response toa change in the power supply voltages supplied to the amplifier 50. Thevariable matching circuit 60 includes one or more inductor elements andone or more capacitor elements. At least one of the one or morecapacitor elements is a variable capacitor element, or at least one ofthe one or more inductor elements is a variable inductor element. Thevariable matching circuit 60 may have the so-called T-type, π-type, orL-type circuit configuration, for example, and one of an inductorelement and a capacitor element may be connected in series with atransmission signal path or may be shunt-connected between thetransmission signal path and ground. When the variable matching circuit60 includes at least one variable capacitor element, the control circuit120 outputs to the variable matching circuit 60 a control signal foradjusting the capacitance value of the at least one variable capacitorelement so that different output impedance matching conditions of theamplifier 50 for the frequency bands of transmission signals aresatisfied on the basis of frequency information received from thebaseband IC 20. The variable matching circuit 60 adjusts the capacitancevalue of the variable capacitor element on the basis of the controlsignal received from the control circuit 120. When the variable matchingcircuit 60 includes a variable inductor element, the control circuit 120outputs to the variable matching circuit 60 a control signal foradjusting the inductance value of the variable inductor element so thatdifferent output impedance matching conditions of the amplifier 50 forthe frequency bands of transmission signals are satisfied on the basisof frequency information received from the baseband IC 20. The variablematching circuit 60 adjusts the inductance value of the variableinductor element on the basis of the control signal received from thecontrol circuit 120. When the variable matching circuit 60 includes avariable capacitor element, the control circuit 120 may output to thevariable matching circuit 60 a control signal for adjusting thecapacitance value of the variable capacitor element so that differentoutput impedance matching conditions of the amplifier 50 for thefrequency bands of transmission signals are satisfied on the basis offrequency information received from the RFIC 30 instead of from thebaseband IC 20. When the variable matching circuit 60 includes avariable inductor element, the control circuit 120 may output to thevariable matching circuit 60 a control signal for adjusting theinductance value of the variable inductor element so that differentoutput impedance matching conditions of the amplifier 50 for thefrequency bands of transmission signals are satisfied on the basis offrequency information received from the RFIC 30 instead of from thebaseband IC 20.

The band switch 70 and the antenna switch 90 selectively switch atransmission signal path and a reception signal path in response toswitching signals supplied from the control circuit 120. Specifically, atransmission signal path is selectively switched so that the first,second, and third transmission signals output from the amplifiers 40 and50 are directed to the antenna 100 via the duplexers 81, 82, and 83,respectively. Likewise, a reception signal path is selectively switchedso that first, second, and third reception signals received from theantenna 100 are directed to the reception module 800 via the duplexers81, 82, and 83, respectively. The first, second, and third receptionsignals are RF signals in different frequency bands. The duplexer 81 isa separator that separates the first transmission signal and the firstreception signal from each other. Likewise, the duplexer 82 is aseparator that separates the second transmission signal and the secondreception signal from each other, and the duplexer 83 is a separatorthat separates the third transmission signal and the third receptionsignal from each other. The reception module 800 low-noise amplifies areception signal and inputs the resulting signal to the RFIC 30. Thereception signal input to the RFIC 30 is demodulated into a basebandsignal by the baseband IC 20.

Next, a method how different output impedance matching conditions of theamplifier 50 for the frequency bands of transmission signals aresatisfied on the basis of a change in the output impedance matchingconditions of the amplifier 50 in response to a change in the powersupply voltages supplied to the amplifier 50 will be described withreference to FIGS. 2 and 3. FIGS. 2 and 3 illustrate simulation resultsdepicting the locus of the impedance of the variable matching circuit 60that includes a variable capacitor element on a Smith chart. It isassumed here that a first power supply voltage is set as a power supplyvoltage for the amplifier 50 which is required to amplify the firsttransmission signal in the first frequency band and that a second powersupply voltage is set as a power supply voltage for the amplifier 50which is required to amplify the second transmission signal in thesecond frequency band, where the transmission output levels areconstant. In FIGS. 2 and 3, numeral 201 denotes the locus of theimpedance of the variable matching circuit 60 on a Smith chart when thecapacitance of the variable capacitor element is changed for the firstfrequency band under a condition where the first power supply voltage issupplied as the power supply voltage for the amplifier 50. In FIG. 2,numeral 202 denotes the locus of the impedance of the variable matchingcircuit 60 on a Smith chart when the capacitance of the variablecapacitor element is changed for the second frequency band under acondition where the first power supply voltage is supplied as the powersupply voltage for the amplifier 50. In FIG. 3, numeral 203 denotes thelocus of the impedance of the variable matching circuit 60 on a Smithchart when the capacitance of the variable capacitor element is changedfor the second frequency band under a condition where the second powersupply voltage is supplied as the power supply voltage for the amplifier50.

The simulation results illustrated in FIG. 2 indicate that, under thecondition where the first power supply voltage is supplied as the powersupply voltage for the amplifier 50, the capacitance value of thevariable capacitor element in the variable matching circuit 60 thatsatisfies the output impedance matching condition required for theamplifier 50 for the first frequency band is determined. However, underthe condition where the first power supply voltage is supplied as thepower supply voltage for the amplifier 50, it is difficult to satisfythe output impedance matching condition required for the amplifier 50for the second frequency band regardless of the capacitance value of thevariable capacitor element in the variable matching circuit 60. Incontrast, the simulation results illustrated in FIG. 3 indicate that,under the condition where the second power supply voltage is supplied asthe power supply voltage for the amplifier 50, the capacitance value ofthe variable capacitor element in the variable matching circuit 60 thatsatisfies the output impedance matching condition required for theamplifier 50 for the second frequency band is determined. Accordingly,when the variable matching circuit 60 includes a variable capacitorelement, different output impedance matching conditions of the amplifier50 for the frequency bands of transmission signals can be satisfied bychanging the capacitance value of the variable capacitor element on thebasis of a change in the output impedance matching conditions of theamplifier 50 in response to a change in the power supply voltagessupplied to the amplifier 50. In this case, the capacitance values ofthe capacitor elements of the variable matching circuit 60, other thanthe variable capacitor element, may remain fixed to constant values andthe inductance values of the inductor elements of the variable matchingcircuit 60 may remain fixed to constant values. In FIGS. 2 and 3, 50Ωrepresents matched impedance.

On the basis of a similar principle, when the variable matching circuit60 includes at least one variable inductor element, different outputimpedance matching conditions of the amplifier 50 for the frequencybands of transmission signals can be satisfied by changing theinductance value of the at least one variable inductor element on thebasis of a change in the output impedance matching conditions of theamplifier 50 in response to a change in the power supply voltagessupplied to the amplifier 50. In this case, the inductance values of theinductor elements of the variable matching circuit 60, other than thevariable inductor element, may remain fixed to constant values, and thecapacitance values of the capacitor elements of the variable matchingcircuit 60 may remain fixed to constant values. The variable matchingcircuit 60 may include both a variable capacitor element and a variableinductor element. Different output impedance matching conditions of theamplifier 50 for the frequency bands of transmission signals can also besatisfied by changing both the capacitance value of the variablecapacitor element and the inductance value of the variable inductorelement in accordance with a change in the output impedance matchingconditions of the amplifier 50 in response to a change in the powersupply voltages supplied to the amplifier 50.

FIG. 4 illustrates the circuit configuration of the transmission andreception module 10 that includes a variable capacitor element as acircuit element of the variable matching circuit 60. The variablematching circuit 60 includes inductor elements L1 and L2, which areconnected in series with the transmission signal path, and capacitorelements C1 and C2, which are shunt-connected between the transmissionsignal path and ground. The inductor elements L1 and L2 are fixedinductor elements whose inductance values are fixed to constant values.The capacitor element C1 is a fixed capacitor element whose capacitancevalue is fixed to a constant value. The capacitor element C2 is avariable capacitor element including a plurality of fixed capacitorelements C21, C22, and C23 having different capacitance values, and aswitch 130 that selectively switches the connections between thetransmission signal path and the fixed capacitor elements C21, C22, andC23. Note that the variable matching circuit 60 illustrated in FIG. 4includes no variable inductor element. In FIG. 4, by way of example, thenumber of fixed capacitor elements C21, C22, and C23 is equal to thenumber of frequency bands of transmission signals. The number of fixedcapacitor elements included in the capacitor element C2 may be largerthan the number of frequency bands of transmission signals. The fixedinductor elements L1 and L2 are optional to the variable matchingcircuit 60 and may not be included in the variable matching circuit 60.The control circuit 120 outputs to the switch 130 a control signal forselecting a fixed capacitor element to be connected to the signal pathfrom among the plurality of fixed capacitor elements C21, C22, and C23so that different output impedance matching conditions of the amplifier50 for the frequency bands of transmission signals are satisfied on thebasis of frequency information received from the baseband IC 20. Theswitch 130 connects the selected fixed capacitor element to the signalpath on the basis of the control signal received from the controlcircuit 120. The fixed capacitor elements C21, C22, and C23 havecapacitance values of, for example, 3.5 pF, 3.3 pF, and 3.1 pF,respectively. The capacitor element C21 is selected for amplifying thefirst transmission signal in the first frequency band (for example, the700 MHz band). The capacitor element C22 is selected for amplifying thesecond transmission signal in the second frequency band (for example,the 800 MHz band). The capacitor element C23 is selected for amplifyingthe third transmission signal in the third frequency band (for example,the 900 MHz band). As given in Table 2, the higher the frequency band ofthe transmission signal, the smaller the capacitance value of the fixedcapacitor element to be selected.

TABLE 2 Frequency band Power mode 700 MHz band 800 MHz band 900 MHz bandAll output modes 3.5 pF 3.3 pF 3.1 pF

In the example given in Table 2, the capacitance value of the variablecapacitor element in the variable matching circuit 60 is set to aconstant value for all the power modes, in common, to amplifytransmission signals in an identical frequency band, for convenience ofdescription. The capacitance value of the variable capacitor element inthe variable matching circuit 60 may be changed in accordance with thepower mode even when transmission signals in an identical frequency bandare amplified.

As indicated by numeral 140, the capacitor element C2 serving as avariable capacitor element and the band switch 70 are formed on anidentical semiconductor substrate by using integration technology suchas monolithic microwave integrated circuit technology, which can lead toa reduction in module area.

FIG. 5 illustrates the circuit configuration of the transmission andreception module 10 that includes a variable inductor element as acircuit element of the variable matching circuit 60. The variablematching circuit 60 includes inductor elements L3 and L4, which areconnected in series with the transmission signal path, and capacitorelements C3 and C4, which are shunt-connected between the transmissionsignal path and ground. The inductor element L3 is a fixed inductorelement whose inductance value is fixed to a constant value. Thecapacitor elements C3 and C4 are fixed capacitor elements whosecapacitance values are fixed to constant values. The inductor element L4is a variable inductor element including a plurality of fixed inductorelements L41, L42, and L43 having different inductance values, and aswitch 150 that selectively switches the connections between thetransmission signal path and the fixed inductor elements L41, L42, andL43. Note that the variable matching circuit 60 illustrated in FIG. 5includes no variable capacitor element. In FIG. 5, by way of example,the number of fixed inductor elements L41, L42, and L43 is equal to thenumber of frequency bands of transmission signals. The number of fixedinductor elements included in the inductor element L4 may be larger thanthe number of frequency bands of transmission signals. The fixedcapacitor elements C3 and C4 are optional to the variable matchingcircuit 60 and may not be included in the variable matching circuit 60.The control circuit 120 outputs to the switch 150 a control signal forselecting a fixed inductor element to be connected to the signal pathfrom among the plurality of fixed inductor elements L41, L42, and L43 sothat different output impedance matching conditions of the amplifier 50for the frequency bands of transmission signals are satisfied on thebasis of frequency information received from the baseband IC 20. Theswitch 150 connects the selected fixed inductor element to the signalpath on the basis of the control signal received from the controlcircuit 120. The inductor elements L41, L42, and L43 have inductancevalues of, for example, 3.8 nH, 4 nH, and 4.2 nH, respectively. Theinductor element L41 is selected for amplifying the first transmissionsignal in the first frequency band (for example, the 700 MHz band). Theinductor element L42 is selected for amplifying the second transmissionsignal in the second frequency band (for example, the 800 MHz band). Theinductor element L43 is selected for amplifying the third transmissionsignal in the third frequency band (for example, the 900 MHz band). Asgiven in Table 3, the higher the frequency band of the transmissionsignal, the larger the inductance value of the inductor element to beselected.

TABLE 3 Frequency band Power mode 700 MHz band 800 MHz band 900 MHz bandAll output modes 3.8 nH 4 nH 4.2 nH

In the example given in Table 3, the inductance value of the variableinductor element in the variable matching circuit 60 is set to aconstant value for all the power modes, in common, to amplifytransmission signals in an identical frequency band, for convenience ofdescription. The inductance value of the variable inductor element inthe variable matching circuit 60 may be changed in accordance with thepower mode even when transmission signals in an identical frequency bandare amplified.

As indicated by numeral 160, the inductor element L4 serving as avariable inductor element and the band switch 70 are formed on anidentical semiconductor substrate by using integration technology suchas monolithic microwave integrated circuit technology, which can lead toa reduction in module area.

In the transmission module 700 according to the first embodiment, thevariable matching circuit 60 can satisfy different output impedancematching conditions of the amplifier 50 for the frequency bands oftransmission signals by changing the capacitance value of the variablecapacitor element or the inductance value of the variable inductorelement on the basis of a change in the output impedance matchingconditions of the amplifier 50 in response to a change in the powersupply voltages supplied to the amplifier 50. This eliminates the needfor combinations of output impedance matching circuits and poweramplifiers, each of which is optimized to amplify signals in apredetermined frequency band, to be provided for respective frequencybands, thereby reducing the number of elements in the transmissionmodule 700, which further contributes to a reduction in the size of thetransmission module 700. In addition, the variable matching circuit 60can satisfy different output impedance matching conditions of theamplifier 50 for the frequency bands of transmission signals byadjusting either the inductance value of the variable inductor elementor the capacitance value of the variable capacitor element. Thiseliminates the need to adjust both the inductance value of the variableinductor element and the capacitance value of the variable capacitorelement. Thus, the circuit configuration of the variable matchingcircuit 60 can be simplified. Furthermore, formation of the band switch70 and the capacitor element C2 serving as a variable capacitor elementon an identical semiconductor substrate can reduce the module area.Alternatively, formation of the band switch 70 and the inductor elementL4 serving as a variable inductor element on an identical semiconductorsubstrate can reduce the module area.

FIG. 6 illustrates the circuit configuration of a transmission andreception module 300 according to a second embodiment of the presentdisclosure. The same numerals as those illustrated in FIG. 1 are used toindicate the same or substantially the same circuit elements, and thefollowing description focuses on the difference between the first andsecond embodiments. A transmission module 700 according to the secondembodiment is different from the transmission module 700 according tothe first embodiment in that the transmission module 700 according tothe second embodiment includes a power supply voltage regulator circuit170 and a variable matching circuit 180. The control circuit 120receives frequency information and power mode information from thebaseband IC 20. The frequency information indicates the frequencies ofthe respective transmission signals, and the power mode informationindicates the transmission output levels of the respective transmissionsignals. The control circuit 120 controls the power supply voltageregulator circuit 110 so that the power supply voltage to be suppliedfrom the power supply voltage regulator circuit 110 to the amplifier 50is regulated on the basis of the frequency information and power modeinformation received from the baseband IC 20. Likewise, the controlcircuit 120 controls the power supply voltage regulator circuit 170 sothat the power supply voltage to be supplied from the power supplyvoltage regulator circuit 170 to the amplifier 40 is regulated on thebasis of the frequency information and power mode information receivedfrom the baseband IC 20. The power supply voltage regulator circuit 170is, for example, a DC/DC converter for boosting or stepping down adirect-current (DC) voltage serving as a power supply voltage to besupplied to the amplifier 40. Table 4 gives an example of power supplyvoltages for the amplifier 40 that are regulated on the basis offrequency information and power mode information. The control circuit120 may control the power supply voltage regulator circuit 170 so thatthe power supply voltage to be supplied from the power supply voltageregulator circuit 170 to the amplifier 40 is regulated on the basis offrequency information and power mode information received from the RFIC30 instead of from the baseband IC 20.

TABLE 4 Frequency band Power mode 700 MHz band 800 MHz band 900 MHz bandAll output modes 3.3 V 3.4 V 3.5 V

In the example given in Table 4, a power supply voltage for theamplifier 40 which is required to amplify a transmission signal is setto a higher voltage value for a higher transmission frequency. By way ofexample, the power supply voltage for the amplifier 40 is set to aconstant value for all the power modes, in common, to amplifytransmission signals in an identical frequency band, for convenience ofdescription. The power supply voltage for the amplifier 40 may bechanged in accordance with the power mode even when transmission signalsin an identical frequency band are amplified.

The variable matching circuit 180 is designed to satisfy differentimpedance matching conditions between the amplifier 40 and the amplifier50 for the frequency bands of transmission signals, on the basis of achange in the impedance matching conditions between the amplifier 40 andthe amplifier 50 in response to a change in the power supply voltagessupplied to the amplifier 40. The variable matching circuit 180 includescapacitor elements C5 and C6, which are connected in series with thetransmission signal path, and an inductor element L5, which isshunt-connected between the transmission signal path and ground. Thecapacitor element C6 is a fixed capacitor element whose capacitancevalue is fixed to a constant value. The inductor element L5 is a fixedinductor element whose inductance value is fixed to a constant value.The capacitor element C5 is a variable capacitor element whosecapacitance value can be changed on the basis of the control signalreceived from the control circuit 120. Note that the variable matchingcircuit 180 illustrated in FIG. 6 includes no variable inductor element.The control circuit 120 outputs to the variable matching circuit 180 acontrol signal for adjusting the capacitance value of the variablecapacitor element C5 in the variable matching circuit 180 so thatdifferent impedance matching conditions between the amplifier 40 and theamplifier 50 for the frequency bands of transmission signals aresatisfied on the basis of frequency information received from thebaseband IC 20. The variable matching circuit 180 adjusts thecapacitance value of the variable capacitor element C5 on the basis ofthe control signal received from the control circuit 120. As given inTable 5, the variable matching circuit 180 adjusts the capacitance valueof the variable capacitor element C5 to 18 pF, for example, foramplifying the first transmission signal in the first frequency band(for example, the 700 MHz band). The variable matching circuit 180adjusts the capacitance value of the variable capacitor element C5 to 15pF, for example, for amplifying the second transmission signal in thesecond frequency band (for example, the 800 MHz band). The variablematching circuit 180 adjusts the capacitance value of the variablecapacitor element C5 to 12 pF, for example, for amplifying the thirdtransmission signal in the third frequency band (for example, the 900MHz band). As given in Table 5, the higher the frequency band of thetransmission signal, the smaller the capacitance value of the variablecapacitor element C5 in the variable matching circuit 180. The controlcircuit 120 may output to the variable matching circuit 180 a controlsignal for adjusting the capacitance value of the variable capacitorelement C5 in the variable matching circuit 180 so that differentimpedance matching conditions between the amplifier 40 and the amplifier50 for the frequency bands of transmission signals are satisfied on thebasis of frequency information received from the RFIC 30 instead of fromthe baseband IC 20.

TABLE 5 Frequency band Power mode 700 MHz band 800 MHz band 900 MHz bandAll output modes 18 pF 15 pF 12 pF

In the example given in Table 5, the capacitance value of the variablecapacitor element C5 in the variable matching circuit 180 is set to aconstant value for all the power modes, in common, to amplifytransmission signals in an identical frequency band, for convenience ofdescription. The capacitance value of the variable capacitor element C5may be changed in accordance with the power mode even when transmissionsignals in an identical frequency band are amplified.

The circuit configuration of the variable matching circuit 180 is notlimited to the circuit configuration illustrated in FIG. 6. For example,the variable matching circuit 180 may include one or more inductorelements and one or more capacitor elements so long as at least one ofthe one or more capacitor elements is a variable capacitor element or atleast one of the one or more inductor elements is a variable inductorelement. The variable matching circuit 180 may include, for example, atleast one variable capacitor element and at least one fixed inductorelement, but may not necessarily include a variable inductor element.Alternatively, the variable matching circuit 180 may include at leastone fixed capacitor element and at least one variable inductor element,but may not necessarily include a variable capacitor element. Thevariable matching circuit 180 may have the so-called T-type, π-type, orL-type circuit configuration, for example, and one of an inductorelement and a capacitor element may be connected in series with atransmission signal path or may be shunt-connected between thetransmission signal path and ground. In this case, the control circuit120 outputs to the variable matching circuit 180 a control signal foradjusting the capacitance value of at least one variable capacitorelement or the inductance value of at least one variable inductorelement so that different impedance matching conditions between theamplifier 40 and the amplifier 50 for the frequency bands oftransmission signals are satisfied on the basis of frequency informationreceived from the baseband IC 20. In response to the control signalreceived from the control circuit 120, the variable matching circuit 180adjusts the capacitance value of the variable capacitor element or theinductance value of the variable inductor element.

In the transmission module 700 according to the second embodiment,different power supply voltages for the frequency bands of transmissionsignals are supplied to the amplifier 40, thereby enabling the amplifier40 to operate under optimum conditions. In addition, different impedancematching conditions between the amplifier 40 and the amplifier 50 forthe frequency bands of transmission signals are satisfied using thevariable matching circuit 180, thereby enabling the amplifiers 40 and 50to operate under optimum conditions. The variable matching circuit 180can satisfy different impedance matching conditions between theamplifier 40 and the amplifier 50 for the frequency bands oftransmission signals by adjusting the capacitance value of the variablecapacitor element C5. This eliminates the need to adjust both theinductance value of a variable inductor element and the capacitancevalue of the variable capacitor element C5. Thus, the circuitconfiguration of the variable matching circuit 180 can be simplified.

The power supply voltage regulator circuit 170 and the variable matchingcircuit 180 may be included in the transmission and reception modules 10illustrated in FIGS. 4 and 5 or may be included in transmission andreception modules 500 and 600 illustrated in FIG. 8 and FIG. 9.

FIG. 7 illustrates the circuit configuration of a transmission andreception module 400 according to a third embodiment of the presentdisclosure. The same numerals as those illustrated in FIG. 1 are used toindicate the same or substantially the same circuit elements, and thefollowing description focuses on the difference between the first andthird embodiments. A transmission module 700 according to the thirdembodiment is different from the transmission module 700 according tothe first embodiment in that the transmission module 700 according tothe third embodiment includes a plurality of amplifiers 41, 42, and 43serving as driver stage amplifiers, a plurality of inter-stage matchingcircuits 181, 182, and 183, and a band switch 190.

The amplifier 41 and the inter-stage matching circuit 181 are optimallydesigned in advance to amplify the first transmission signal in thefirst frequency band. The control circuit 120 outputs to the band switch190 a control signal for switching a device to which the band switch 190is connected so that the first transmission signal output from the RFIC30 is input to the amplifier 50 via the amplifier 41 and the inter-stagematching circuit 181 on the basis of frequency information received fromthe baseband IC 20. In response to the control signal from the controlcircuit 120, the band switch 190 switches a device to which the bandswitch 190 is connected so that the amplifier 41 is selectivelyconnected to the stage preceding the amplifier 50 via the inter-stagematching circuit 181 for amplifying the first transmission signal. Theinter-stage matching circuit 181 matches impedance between the amplifier41 and the amplifier 50.

The amplifier 42 and the inter-stage matching circuit 182 are optimallydesigned in advance to amplify the second transmission signal in thesecond frequency band. The control circuit 120 outputs to the bandswitch 190 a control signal for switching a device to which the bandswitch 190 is connected so that the second transmission signal outputfrom the RFIC 30 is input to the amplifier 50 via the amplifier 42 andthe inter-stage matching circuit 182 on the basis of frequencyinformation received from the baseband IC 20. In response to the controlsignal from the control circuit 120, the band switch 190 switches adevice to which the band switch 190 is connected so that the amplifier42 is selectively connected to the stage preceding the amplifier 50 viathe inter-stage matching circuit 182 for amplifying the secondtransmission signal. The inter-stage matching circuit 182 matchesimpedance between the amplifier 42 and the amplifier 50.

The amplifier 43 and the inter-stage matching circuit 183 are optimallydesigned in advance to amplify the third transmission signal in thethird frequency band. The control circuit 120 outputs to the band switch190 a control signal for switching a device to which the band switch 190is connected so that the third transmission signal output from the RFIC30 is input to the amplifier 50 via the amplifier 43 and the inter-stagematching circuit 183 on the basis of frequency information received fromthe baseband IC 20. In response to the control signal from the controlcircuit 120, the band switch 190 switches a device to which the bandswitch 190 is connected so that the amplifier 43 is selectivelyconnected to the stage preceding the amplifier 50 via the inter-stagematching circuit 183 for amplifying the third transmission signal. Theinter-stage matching circuit 183 matches impedance between the amplifier43 and the amplifier 50.

In the transmission module 700 according to the third embodiment, eachof the amplifiers 41, 42, and 43 can be selectively connected to thestage preceding the amplifier 50 via the corresponding one of theinter-stage matching circuits 181, 182, and 183 that are determined inadvance in accordance with the frequency band of the transmissionsignal. This configuration enables the amplifiers 41, 42, and 43 in thedriver stage and the amplifier 50 in the output stage to operate underoptimum conditions.

The amplifiers 41, 42, and 43 and the inter-stage matching circuits 181,182, and 183 may be included in place of the amplifier 40 in thetransmission and reception modules 10 illustrated in FIGS. 4 and 5 ormay be included in place of an amplifier 40 in the transmission andreception module 600 illustrated in FIG. 9.

FIG. 8 illustrates the circuit configuration of a transmission andreception module 500 according to a fourth embodiment of the presentdisclosure. The same numerals as those illustrated in FIG. 1 are used toindicate the same or substantially the same circuit elements, and thefollowing description focuses on the difference between the first andfourth embodiments. A transmission module 700 according to the fourthembodiment is different from the transmission module 700 according tothe first embodiment in that the transmission module 700 according tothe fourth embodiment includes a plurality of inter-stage matchingcircuits 181, 182, and 183 and a plurality of band switches 190 and 230.

The plurality of inter-stage matching circuits 181, 182, and 183 areoptimally designed to match impedance between the amplifiers 40 and 50for the frequency bands of the first, second, and third transmissionsignals, respectively. The band switches 190 and 230 selectively switchthe connections between the band switches 190 and 230 and theinter-stage matching circuits 181, 182, and 183 so that the first,second, and third transmission signals output from the amplifier 40 areinput to the amplifier 50 via the inter-stage matching circuits 181,182, and 183, respectively.

The transmission module 700 according to the fourth embodiment includesin advance the plurality of inter-stage matching circuits 181, 182, and183 that are optimally designed to match impedance between theamplifiers 40 and 50 for the frequency bands of the first, second, andthird transmission signals, respectively. This configuration enables theamplifier 40 in the driver stage and the amplifier 50 in the outputstage to operate under optimum conditions.

FIG. 9 illustrates the circuit configuration of a transmission andreception module 600 according to a fifth embodiment of the presentdisclosure. The same numerals as those illustrated in FIG. 1 are used toindicate the same or substantially the same circuit elements, and thefollowing description focuses on the difference between the first andfifth embodiments. The transmission and reception module 600 isdifferent from the transmission and reception module 10 according to thefirst embodiment in that the transmission and reception module 600includes a variable duplexer 200 in place of the band switch 70, theduplexers 81, 82, and 83, and the antenna switch 90 in the transmissionand reception module 10 according to the first embodiment. The variableduplexer 200 includes a transmission filter 210 and a reception filter220. The transmission filter 210 exhibits different frequencycharacteristics for the frequency bands of selected transmission signalssuch that the frequency band of a transmission signal selected fromamong the first, second, and third transmission signals is the pass bandof the transmission filter 210 and the frequency bands of the unselectedtransmission signals are the stop bands of the transmission filter 210.The reception filter 220 exhibits different frequency characteristicsfor the frequency bands of selected reception signals such that thefrequency band of a reception signal selected from among the first,second, and third reception signals is the pass band of the receptionfilter 220 and the frequency bands of the unselected reception signalsare the stop bands of the reception filter 220. The control circuit 120outputs a control signal to the variable duplexer 200 so that theselected transmission signal and reception signal pass through thevariable duplexer 200 on the basis of frequency information receivedfrom the baseband IC 20. In response to the control signal from thecontrol circuit 120, the variable duplexer 200 changes the frequencycharacteristics so that the pass band coincides with the frequency bandof each of the selected transmission signal and reception signal. Thetransmission filter 210 has a transmission signal input node connectedto the amplifiers 40 and 50 via the variable matching circuit 60. Thereception filter 220 has a reception signal output node connected to theRFIC 30 via the reception module 800. A common node of the transmissionfilter 210 and the reception filter 220 is connected to the antenna 100.

The transmission and reception module 600 according to the fifthembodiment is provided with the variable duplexer 200 that exhibits adifferent frequency characteristic for the frequency band of atransmission signal selected from among a plurality of transmissionsignals in such a manner as to allow the selected transmission signal topass through the variable duplexer 200, and can thus have a simplecircuit configuration.

In the transmission and reception modules 10 illustrated in FIGS. 4 and5, the variable duplexer 200 may be used in place of the band switch 70,the duplexers 81, 82, and 83, and the antenna switch 90. Likewise, inthe transmission and reception module 300 illustrated in FIG. 6, thevariable duplexer 200 may be used in place of the band switch 70, theduplexers 81, 82, and 83, and the antenna switch 90. Also, in thetransmission and reception module 400 illustrated in FIG. 7, thevariable duplexer 200 may be used in place of the band switch 70, theduplexers 81, 82, and 83, and the antenna switch 90.

The embodiments described above are intended to help easily understandthe present disclosure, and are not to be used to construe the presentdisclosure in a limiting fashion. Various modifications or improvementscan be made to the present disclosure without necessarily departing fromthe gist of the present disclosure, and equivalents thereof are alsoincluded in the present disclosure. That is, the embodiments may beappropriately modified in design by those skilled in the art, and suchmodifications also fall within the scope of the present disclosure solong as the modifications include the features of the presentdisclosure. The elements included in the embodiments and thearrangement, materials, conditions, shapes, sizes, and the like thereofare not limited to those described in the illustrated examples but canbe modified as appropriate. For instance, the expression “circuitelement A is connected to circuit element B” is used to include not onlythe case where the circuit element A is connected directly to thecircuit element B but also the case where a signal path can beestablished between the circuit element A and the circuit element B viaa circuit element C. Additionally, the positional relationships betweenelements, such as above, below, right-of, and left-of, are not limitedby the dimensional ratios of the elements illustrated in the drawings,unless otherwise stated. Furthermore, the elements included in theembodiments can be combined as much as technically possible, and suchcombinations of elements also fall within the scope of the presentdisclosure so long as the combinations of elements include the featuresof the present disclosure.

While preferred embodiments of the invention have been described above,it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the invention.

The scope of the invention, therefore, is to be determined solely by thefollowing claims.

What is claimed is:
 1. A transmission module comprising: a firstamplifier configured to amplify a plurality of transmission signals indifferent frequency bands; a first power supply voltage regulatorcircuit configured to supply a power supply voltage to the firstamplifier, the power supply voltage to the first amplifier depending ona frequency band of a transmission signal being amplified by the firstamplifier; and a first variable matching circuit having at least onevariable capacitor element and not having any variable inductorelements, wherein the first variable matching circuit is configured tosatisfy output impedance matching conditions of the first amplifierbased on the frequency band of the transmission signal being amplifiedby changing a capacitance value of the at least one variable capacitorelement based on a change in the output impedance matching conditions ofthe first amplifier in response to a change in the power supply voltagesupplied to the first amplifier.
 2. A transmission module comprising: afirst amplifier configured to amplify a plurality of transmissionsignals in different frequency bands; a first power supply voltageregulator circuit configured to supply a power supply voltage to thefirst amplifier, the power supply voltage to the first amplifierdepending on a frequency band of a transmission signal being amplifiedby the first amplifier; and a first variable matching circuit having atleast one variable inductor element and not having any variablecapacitor elements, wherein the first variable matching circuit isconfigured to satisfy output impedance matching conditions of the firstamplifier based on the frequency band of the transmission signal beingamplified by changing an inductance value of the at least one variableinductor element based on a change in the output impedance matchingconditions of the first amplifier in response to a change in the powersupply voltage supplied to the first amplifier.
 3. The transmissionmodule according to claim 1, further comprising: a second amplifierconnected to and preceding the first amplifier; a second power supplyvoltage regulator circuit configured to supply a power supply voltage tothe second amplifier, the power supply voltage to the second amplifierdepending on a frequency band of a transmission signal being amplifiedby the second amplifier; and a second variable matching circuit havingat least one variable capacitor element and not having any variableinductor elements, wherein the second variable matching circuit isconfigured to satisfy impedance matching conditions between the secondamplifier and the first amplifier based on the frequency band of thetransmission signal being amplified by the second amplifier by changinga capacitance value of the at least one variable capacitor element ofthe second impedance matching circuit based on a change in the impedancematching conditions between the second amplifier and the first amplifierin response to a change in the power supply voltage supplied to thesecond amplifier.
 4. The transmission module according to claim 2,further comprising: a second amplifier connected to and preceding thefirst amplifier; a second power supply voltage regulator circuitconfigured to supply a power supply voltage to the second amplifier, thepower supply voltage to the second amplifier depending on a frequencyband of a transmission signal being amplified by the second amplifier;and a second variable matching circuit having at least one variablecapacitor element and not having any variable inductor elements, whereinthe second variable matching circuit is configured to satisfy impedancematching conditions between the second amplifier and the first amplifierbased on the frequency band of the transmission signal being amplifiedby the second amplifier by changing a capacitance value of the at leastone variable capacitor element of the second impedance matching circuitbased on a change in the impedance matching conditions between thesecond amplifier and the first amplifier in response to a change in thepower supply voltage supplied to the second amplifier.
 5. Thetransmission module according to claim 1, further comprising: a secondamplifier connected to and preceding the first amplifier; a second powersupply voltage regulator circuit configured to supply a power supplyvoltage to the second amplifier, the power supply voltage to the secondamplifier depending on a frequency band of a transmission signal beingamplified by the second amplifier; and a second variable matchingcircuit having at least one variable inductor element and not having anyvariable capacitor elements, wherein the second variable matchingcircuit is configured to satisfy impedance matching conditions betweenthe second amplifier and the first amplifier based on the frequency bandof the transmission signal being amplified by the second amplifier bychanging an inductance value of the at least one variable inductorelement of the second impedance matching circuit based on a change inthe impedance matching conditions between the second amplifier and thefirst amplifier in response to a change in the power supply voltagesupplied to the second amplifier.
 6. The transmission module accordingto claim 2, further comprising: a second amplifier connected to andpreceding the first amplifier; a second power supply voltage regulatorcircuit configured to supply a power supply voltage to the secondamplifier, the power supply voltage to the second amplifier depending ona frequency band of a transmission signal being amplified by the secondamplifier; and a second variable matching circuit having at least onevariable inductor element and not having any variable capacitorelements, wherein the second variable matching circuit is configured tosatisfy impedance matching conditions between the second amplifier andthe first amplifier based on the frequency band of the transmissionsignal being amplified by the second amplifier by changing an inductancevalue of the at least one variable inductor element of the secondimpedance matching circuit based on a change in the impedance matchingconditions between the second amplifier and the first amplifier inresponse to a change in the power supply voltage supplied to the secondamplifier.
 7. The transmission module according to claim 1, furthercomprising: a plurality of second amplifiers, each one of the secondamplifiers being selectively connectable to and preceding the firstamplifier via a corresponding one of a plurality of inter-stage matchingcircuits, each one of the inter-stage matching circuits being associatedwith a frequency band of a transmission signal amplified by thecorresponding one of the second amplifiers.
 8. The transmission moduleaccording to claim 2, further comprising: a plurality of secondamplifiers, each one of the second amplifiers being selectivelyconnectable to and preceding the first amplifier via a corresponding oneof a plurality of inter-stage matching circuits, each one of theinter-stage matching circuits being associated with a frequency band ofa transmission signal amplified by the corresponding one of the secondamplifiers.
 9. A transmission and reception module comprising: thetransmission module according to claim 1; and a variable duplexer thatexhibits frequency characteristics according to the frequency band ofthe transmission signal being amplified such that the frequency band ofthe transmission signal being amplified is within a passband of thevariable duplexer.
 10. A transmission and reception module comprising:the transmission module according to claim 2; and a variable duplexerthat exhibits frequency characteristics according to the frequency bandof the transmission signal being amplified such that the frequency bandof the transmission signal being amplified is within a passband of thevariable duplexer.
 11. A transmission and reception module comprising:the transmission module according to claim 3; and a variable duplexerthat exhibits frequency characteristics according to the frequency bandof the transmission signal being amplified such that the frequency bandof the transmission signal being amplified is within a passband of thevariable duplexer.
 12. A transmission and reception module comprising:the transmission module according to claim 4; and a variable duplexerthat exhibits frequency characteristics according to the frequency bandof the transmission signal being amplified such that the frequency bandof the transmission signal being amplified is within a passband of thevariable duplexer.
 13. A transmission and reception module comprising:the transmission module according to claim 5; and a variable duplexerthat exhibits frequency characteristics according to the frequency bandof the transmission signal being amplified such that the frequency bandof the transmission signal being amplified is within a passband of thevariable duplexer.
 14. A transmission and reception module comprising:the transmission module according to claim 6; and a variable duplexerthat exhibits frequency characteristics according to the frequency bandof the transmission signal being amplified such that the frequency bandof the transmission signal being amplified is within a passband of thevariable duplexer.
 15. A transmission and reception module comprising:the transmission module according to claim 7; and a variable duplexerthat exhibits frequency characteristics according to the frequency bandof the transmission signal being amplified such that the frequency bandof the transmission signal being amplified is within a passband of thevariable duplexer.
 16. A transmission and reception module comprising:the transmission module according to claim 8; and a variable duplexerthat exhibits frequency characteristics according to the frequency bandof the transmission signal being amplified such that the frequency bandof the transmission signal being amplified is within a passband of thevariable duplexer.
 17. The transmission module according to claim 1,further comprising: a band switch that directs the transmission signalbeing amplified to an antenna, wherein the at least one first variablecapacitor element and the band switch are on a same semiconductorsubstrate.
 18. The transmission module according to claim 2, furthercomprising: a band switch that directs the transmission signal beingamplified to an antenna, wherein the at least one first variableinductor element and the band switch are on a same semiconductorsubstrate.
 19. The transmission module according to claim 1, wherein thefirst power supply voltage regulator circuit is configured to boost abattery voltage to the power supply voltage, the power supply voltagebeing greater than the battery voltage.
 20. The transmission moduleaccording to claim 2, wherein the first power supply voltage regulatorcircuit is configured to boost a battery voltage to the power supplyvoltage, the power supply voltage being greater than the batteryvoltage.